Hydraulic stitcher



R. E. HAGER HYDRAULIC STITCHER May 5, 1959 Filed Jan. 11, .195e

4 Sheets-Shea?l 1 INVENTOR. v

May 5, 1959v R. E. HAGER 2,884,635

HYDRAULIC STITCHER I 4 Sheets-Sheet 2 Filed Jan. l1, 1956 60 53 61h 61 52@ g 655 5g 61 63C. 30 37 66a 6g nir-- l u I i *n INVENTOR.

obeftwgef BY RI E. HAGER HYDRAULIC STITCHER May 5, 1959y Filed Jan. 11, 1956 y 4 Sheets-Sheet 3 hm, um,

United States Patent O P HYDRAULIC STIT CHER Robert E. Hager, Park Forest, Ill., assignor to Acme Steel Company, Chicago, Ill., a corporation of Illinois Application January 11, 1956, Serial No. 558,508 v14 claims. (cl. .1 -44.4)

This invention relates' to stitching machines adapted for use in forming and driving metal staples made of sections of stitching wire and the purpose of the present invention is to provide an improved stitcher of this type which is operated by yhydraulic power.

lIn machines of this type it is common practice to employ a pair of staple formers which descend toward the work and lbend over -an anvil the end portions of a length of stitching wire which has been cut from a supply, thereby forming -a staple which is then driven into the 'work and clinched on theunderside of the work. When such a machine is employed in stitching material which cannot be readily penetrated by the staple legs, such as heavy fibreboard, sheet' metal and the like, it has been found desirable to cau'se the staple formers -to bear on the work piece with substantialpressure in order to assure the proper driving and clinching of the staple. That result has been achieved by means of mechanical adjustments for varying the stroke of the stapleformers or the position of the clinching anvil, b-ut they have the disadvantages that the operation of the machine must 'be arrested in order to make 'the adjustments or else an adjustably positioned clinching anvil support must be `provided.

T he principal object of the present invention is to provide a stitching machine lhaving formers operated by hydraulic pressure so 'that fthe required high degree of pressure of the formers on the workpiece vmay be obtained while at the 'same time making it possible to regulate the former vpressure by adjusting the hydraulic pressure without stopping the machine or adjusting the clinching anvil. A further object of the `invention Yis to provide a stitching machine in which the staple .former andthe staple driver are both operated in proper timed relation by hydraulic pressure. Another object is to provide a stitching machine having a former and ydriver operated by a two pressure hydraulic system embodying means for varying the pressure lapplied to the former by adjusting an ordinary relief valve while themachine is in operation. Other ob- Vjects relate tov various features of construction and arrangement which will appear more fully hereinafter.

The nature of the invention will be understood from lthe following specification taken with the accompanying drawings in whichfone embodiment is illustrated. ln the drawings,

Figure 1 shows-a side elevation of the stitching unit of the improved hydraulic stitching mechanism lof the present invention with a portion-of the stitching device shown in vertical section;

Fig. 2 shows a front elevation Aof the stitching device illustrated in Fig. 1 with a portion thereof shown in vertical section on the line 2-2 of Fig. 1;

Fig. 3 shows a horizontal section taken on the line 3 3 of Fig. l

Fig. 4 shows a vsomewhat diagrammatic view of the hydraulic stitcher connected to the hydraulic pressure system -by which `it is operated and illustratingin their 2,884,635 Patented May 5, 1959 retracted positions the pistons for operatiing the staple former and the staple driver;

Fig. 5 shows a somewhat diagrammatic vertical section through the cylinder of the stitching machine illustrating the pistons in their retracted positions shown in Fig. 4;

Fig. 6 is a sectional view similar to that vof Fig.'5 showing the relative positions of the pistons for actuating the staple former and the staple driver after the staple former has reached the end of its working stroke;

Fig. 7 is a sectional view similar to those of Figs. 5 and 6 illustrating the relative positions of the pistons in the cylinder after the staple has been formed and driven;

Fig. 8 is a somewhat diagrammatic sectional view similar to that of Fig. 4 illustrating the relative positions of the parts after the hydraulic Huid has been admitted to the cylinder to cause the forward strokes of both of the pistons, while at the same time causing the retraction of the wire feeding piston; and

Fig. 9 is a somewhat diagrammatic sectional View similar to those of Figs. 4 and 8 illustrating the relative positions of the parts and the direction of ow of hydraulic iluid when the pistons have been returned to their retractedpositions and after the wire feeding piston has been moved through a feeding stroke.

Before referring to the hydraulic system by which the stitching operations are effected, reference will be made to the stitching unit which is shown particularly in Figs. 1, 2 and 3. This unit comprises a frame or casing 10 having formed therein a cylinder 10a in Wh-ich there is mounted a piston 11 for actuating the staple formers and another piston 12 for actuating the staple dri-ver. This frame 1t) has clamped thereon a handle 13 by which the stitcher may be moved about by the operator and this handle has formed on the upper end thereof a hook '14 by which the device may be suspended on a suitable support.

The piston 11 is mounted to slide in a tubular bore 10c formed in the lower part of the casing and it is provided at its upper` end with an outwardly extending annular ange 11a which is of lesser diameter than the cylinder 10a and which is adapted to engage the shoulder ltlb at the lower end of the cylinder when this piston is at the extreme lower or forward end of its stroke. The piston 11 is further provided with an internal cylindrical bore 11b which is slidably engaged by a piston rod 15 secured at its lupper end to the piston 12. In order to maintain lHuid-tight connections between the relatively movable parts, the casing 10 is provided with -an internal annular groove 10d in which there is mounted a packing ring 16 adapted to bear upon the outer surface of the piston 11. Similarly, the piston 11 is provided with an internal annular groove 11e in which there is mounted a packing ring 17 adapted to bear upon the `outer surface ofthe piston rod 15. The piston 12 is also provided with an annular groove 12a in which there is mounted a packing ring 18 adapted to bear upon the surface of `the cylinder 10a. The cylinder 18a is closed at its upper end by a top plate or cap member 20 which is secured to the -upper end of the casing 10 by means of cap screws 21 upon which spring washers 22 are mounted.

The lower end of the piston 11 is bifurcatedas shown at 11d and the arms which are thus formed are secured by studs 23 to the staple formers 24. These staple formers are provided on their outer sides with grooves 24a which are engaged by ribs 10e formed on the depending side plates 10jc of the casing 10. The inner edges of the staple formers 24 are provided with longitudinal grooves 24b which `are slidably engaged by ribs 25a formed on the lateral edges of the staple driver 25 which is secured to the lower end of the piston rod 15 by means of a pin 26.

When the staple formers 24 descend in response to hydraulic pressure in the cylinder a, they are adapted to engage the stapling wire 30 which is adapted to be fed through a sleeve 31 extending through one of the side plates 103 of the casing near the lower end thereof. This sleeve 31 is secured by a set screw 32 in a tubular passage formed in a bracket 33 which is secured to the adjacent side plate 10JC by studs 34. The bracket 33 has an outwardly extending arm 33a on which are mounted two grooved rollers 35 adapted to engage the upper side of thewire 30 and the lower side of the wire passes over a curved plate 36 having a flange 36a provided with an elongated slot 36b in which there is mounted a set screw 37 by which the elevation of the plate 36 may be varied so that this plate will cooperate with the rollers 35 in straightening the wire 30 as it approaches the sleeve 31. The bracket 33a is provided at its outer end with a block 33b in which one end of a helically wound ilexible tube 37 Iis secured by a set screw 38. The stitching wire 30 is fed through the tube 37 in the manner hereinafter described so that its extremity is projected through the sleeve 31 into the path of the nearer one of the two formers 24. As the former descends, its outer edge acts as a shearing die to cooperate with the inner end of the sleeve to shear the stitching wire and thus cut oft a length or section of wire adapted to be formed into a staple.

As the formers 24 continue to descend, after cutting oi the wire, the end portions of this length of wire are engaged by grooves 24C formed in the lower ends of the formers and these ends are then bent downwardly about an anvil 40 which is pivoted on a pin 41 secured in the side plates 10jc of the casing, as shown particularly in Fig. 1. This anvil is provided at its lower end with a notch or recess 40a through which the stitching wire 30 is passed as it is projected through the sleeve 31. This feeding movement continues until the extremity of the wire engages the side wall 10]c which is opposite to the sleeve 31 and then, upon downward movement of the formers 24, the ends of the section of wire which has been cut off by the initial downward movement are bent over the lower portion 40b of the anvil, thereby forming a U-shaped staple having legs which lie in the side grooves 24b of the formers. The anvil 40 is normally projected to the operating position shown in Fig. l by means of a coil spring 42 which is seated in a recess 40C formed in the anvil and in another recess formed in the back wall 10g of the casing. The operating position of the portion 40b of the anvil may be regulated by a set screw 43 which threadedly engages an aperture in the back wall 10g of the casing and which bears against the upper extremity 40a` of the anvil. This set screw may be secured in adjusted position by a lock nut 44.

The lower end of the piston rod 15, which is actuated by the piston 12, is provided with a projection 15a on which the previously described staple driver 25 is secured by the pin 26. The staple driver 25 is of oblong rectangular form and its lower end is provided with a transversely extending groove 25h which is adapted to engage the top wall of the staple when the driver descends in response to the admission of hydraulic pressure to the region above the piston 12. The staple formers normally descend in response to fluid pressure acting upon the piston 11 until the lower ends bear upon the work to be stitched or until the top ange 11a of the piston 11 engages the shoulder 10b of the casing. In the initial stages of the forward strokes of the pistons, the two pistons 11 and 12 move together with a relatively low pressure applied to the upper end of the piston 11 and with a higher pressure applied to the upper face of the piston 12. They continue to move in unison with the lower end of the piston 11 engaging a pin 45 which is secured in the lower projecting portion of the piston rod 15, and after the formers 24 have engaged the work,

or after the ange 11a has engaged the shoulder 10b, the formers 24 remain stationary on the work and the piston 12 continues its downward movement under the iniiuence of the pressure applied to the upper side thereof thus causing the driver 25 to drive the staple legs through the work.

In order to effect the clinching of the staple legs on the underside of the work piece, there is provided a bracket 47 comprising a plate 47a which is secured to the back wall 10g of the casing by means of cap screws 48, the heads of which engage spring washers 49a. The bracket 47 comprises two parallel U-shaped plates 47b terminating in horizontal forward extensions 47c between which the clinching anvil 49 is secured by a bolt 50. The clinching anvil 49 is mounted between the horizontally extending portions 47b of the parallel arms 47e of the bracket 47 and this anvil is provided on its upper side with curved recesses 49a which are adapted to be engaged by the ends of the staple legs as the staple is driven so that the legs are automatically curved inwardly toward each other and clinched on the underside of the work piece.

The top plate or cap member 20 has formed integrally therewith a cylinder 52 to one end of which hydraulic yfluid under high pressure is admitted through an inlet fitting S3. Hydraulic uid under a comparatively low pressure is admitted to the other end of the cylinder 52 through a fitting 54. The high pressure iluid entering the cylinder 52 through the iitting 53 is adapted to pass to the upper end of the cylinder 10a, above the piston 12, through a port 55. The low pressure fluid, which is admitted to the cylinder 52 through the fitting 54, is adapted to pass -downwardly through a port 56 which communicates with a tube 57 secured in the lower face of the plate 20 and arranged to communicate at its lower end with a fitting 58 which has a passage 58a communieating with the interior of the cylinder 10a around the piston 11 and beneath the piston 12. The hydraulic fluid having two different pressures is thus admitted through these passages to the interior of the cylinder 10a, in the manner hereinafter describiedin order to effect the sequential operation of the pistons 11 and 12 and the actuation of the formers 24 and the driver 25.

The cylinder 52 serves not only as a means for conveying compressed uid to the cylinder 10a, but also as a part of the feeding mechanism by which the stitching wire is fed through the tube 37 to the stitching position. For this purpose, there is provided in the cylinder 52 a reciprocating piston 60 which has a uid-tight connection with the cylinder wall by means of a packing ring 59. The piston 60 is formed integrally with a piston rod 61 which is journalled in a bearing formed in the end wall 52a of the cylinder where a Huid-tight joint is formed by the packing ring 62. The end of the piston -rod 61 opposite the piston 60 is provided with an inwardly extending bore 61a in which there is mounted a tubular guide member 63 having a central passage 63a through which the stitching wire 30 extends. This passage 63a is in alignment with the central passage 61b in the piston rod through which the stitching Wire also extends. At its inner end, the guide member 63 is provided with a cavity 63b having an annular tapered wall 63e` engaged by spherical balls 64 which are `adapted to grip the wire 30 upon movement thereof toward the smaller end of the cavity 63h, a movement which is normally brought about -by a coil spring 65 mounted in the cavity 61C which is formed in the piston rod 61 inwardly from the cavity 63b. When the piston 60 and the piston rod 61 are moved toward the right, as viewed in Fig. 2, the balls 64 are adapted to release the wire 30 but, upon movement of the parts 60 and 61 toward the left, the balls 64 grip the wire and eifect a feeding movementthereof through the tube 37.

'A tubular member 61d which is formed integrally with the piston 60 -and is slidably mounted in a cylindrical s tubular member 66 having at one end an enlargement 66a which seats within the end of the cylinder 52 where it is held in place 4by a locking ring 67. The part 66a has a lluid-tight engagement with the wall of the cylinder 52 Iby means of a packing ring 68 and another packing ring 69 forms a iluid-tight connection between the extension 61d of .the piston rod and the tube 66. At its outer end, the tube 66 is enlarged and provided with a cavity 66b having at its inner end an inclined tapered Wall 66e engaged by spherical iballs 70. A coil spring 71 normally forces the balls 70 .toward the end wall 66d of the cavity. A threaded plug 72 engages the outer enlarged end of the tube 66 and this plug has a passage communicating with the tube 37 which is secured in an internally threaded recess formed Iin the plug. After a feeding movement of the piston 60, toward the left as viewed in Fig. 2, the piston 60 is retracted toward the right and the 'balls 70 then grip the stitching wire 30 -to hold it in the position to which it has been advanced by the previous feeding movement.

In order -to vary the stroke of the wire feeding piston 60, the guide member 63 is externally threaded and is threadedly engaged by a hollow -nut 75 which is secured in adjusted position on the member 63 by means of a nut 76. By varying lthe position of the hollow nut 75 on the member 63, the posi-tion of the piston 60 when it is advanced to its extreme position toward the left, as shown in Fig. 2, may lbe varied with a corresponding variation in the feeding movement which is imparted to the stapling wire 30 Iby the balls 64.

In Figs. 4, 8 and 9, there is shown diagrammatically the hydraulic system 'by which the pistons 11, 12 and 60 are operated. As there shown, the hydraulic fluid, such as oil or water, is contained in a reservoir 77 connected by a conduit 78 to a pump 79 which is operated by an electric motor 80. The motor is adapted to operate continuously when the pump is in use and the pump then withdraws iluid from the reservoir 77 and discharges it under la high pressure through the conduit 81, the pressure in this conduit being indicated by a gage 82. The conduit 81 communicates with a four-way valve 83 adapted to be operated =by a handle 83a. When the valve 83 is in one position it is adapted to discharge iluid under high pressure through :a conduit 84 which leads lthrough the previously described fitting 53 to the cylinder 52 so that high pressure fluid may then enter through the port 55 to the chamber 10a above the piston 12.

When the valve 83 is adjusted to another position the compressed iluid passes through a conduit 85 and a check valve 86 to the fitting 54 leading into the cylinder 52 at the right-hand end thereof as shown in the drawings. The lluid which is thus .admitted through the conduit 85 is at a relatively low pressure due to the action of a pressure relief valve 87 which is connected in a conduit 88 leading from the conduit 85 back to the reservoir 77. By adjusting the relief valve 87, the pressure in the -conduit 85 may -be varied as desired and it is this lluid under this relatively low pressure which passes from the cylinder 52 through the pipe 57 and the fitting 58 to the cylinder 10a in the region between the pistons 11 and 12.

When the stitching machine is at rest preliminary to the lirst stage of its operation, the pistons 11 and 12 are in the positions shown in Figs. 4 and 5 with the piston l2 at the upper end of the cylinder and with low pressure iluid acting upon both pistons so that they are separated until the piston 11 has moved downwardly into engagement with the pin 45. When the valve 83 is then adjusted to admit high pressure lluid through the cylinder 52 and the port 55 to Ithe upper end of the cylinder 10a, both pistons 11 and 12 are moveddownwardly by the high pres-sure iluid which overcomes the low pressure lluid acting upon the underside of the piston 12. Both pistons 11 and 12 then move downwardly until they reach the position shown in Fig. 6 at which time the formers 24 will have bent the ends' of the section vof stapling wire about the anvil 40 to form a U-'sha'ped staple and the lower ends of the formers will be -in engagement with the work piece to hold it iirmly against the work piece resting on the bracket 47 and the clinching anvil 49. Depending upon the character of the work piece, the downward movement of the piston 11 may terminate upon the engagement of the formers with the work piece before the ilange 11a of that piston engages the shoulder 10b of the cylinder but, in Fig. 6, the cylinder 11 is s'hown at its extreme lower position with the flange 11a :resting upon the shoulder of the casing.

With the work piece held -by the formers pressing it against the bracket 47 and the anvil 49, the high pressure fluid acting upon the upper side of the piston 12 causes the downward movement of this piston to continue. At this time the llow of iluid through the conduit and the tube 57 is shut off by the valve and the tluid trapped in the cylinder between the pistons 11 and 12 is further compressed. Slight leakage through the pressure relief valve 87 to the reservoir permits a slight diminution of pressure. As the driver 25 is moved downwardly by the piston 12, the anvil 40 is cammed out of the position shown in Fig. l, Iagainst the compression of the spring 42, by the engagementof the driver 25 with the upper inclined surface 40e of the anvil. The driver then engages the staple and drive-s it through the work piece with the result that the staple legs are clinched upon the clinching anvil 49.

After the forward stroke of the driver has been completed, and the driving and clinching of the staple effected, the valve 83 is again adjusted to connect the conduit 84 through a conduit 90 to the reservoir 77 and low pressure iluid is again admitted through the check valve 86 and the conduit 85 to the space between the pistons 11 and 12 with the result that both pistons ,are again restored to the normal positions shown in Figs. 4 and 9 with the compressed fluid flowing in the direction indicated by the arrows in Fig. 9. The parts are then in readiness Vfor a new operation of the stitching machine which is brought about by again operating the valve 83 to admit fluid to the conduit 81 through the conduit 84 to the upper end of the cylinder 10a.

If the formers 24 do not engage the work piece with suflicient pressure to yhold the work piece rigidly in place during the stapling operation, the degree of this pressure may be regulated while the machine is in operation by the adjustment of the relief valve 87 so that the machine may be 'made to perform 1in the best possible manner without losing any time by stopping the operation of the machine to make an adjustment.

Although one form of the invention has been shown and described by way of illustration, it will be understood that it may be constructed yby various other embodiments which come within the scope of the appended claims.

I claim:

1. A stitching machine comprising, means for supporting a length of stapling wire, a former for bending said wire about said supporting means to form a staple, a driver for driving said staple into the work, means including a piston for actuating said former, means including a second piston for actuating said driver, means for causing fluid of one pressure to actuate said lirst named piston, and means for causing a fluid of another pressure to effect the actuation of said second named piston.

2. A stitching machine comprising, an anvil for supporting a length of stapling wire, .a former for bending said wire over said anvil to form a staple, a driver for driving said staple, a cylinder, a piston in said cylinder for actua-ting said former, a `second piston in said cylinder for `actuating said driver, means for admitting fluid under pressure to said cylinder between said pistons, and means for admitting fluid under a higher pressure to said cylinder on the side of said second named piston opposite that side which is engaged by said lirst named fluid.

3. A stitching machine comprising, an anvil for supporting a length of stapling wire, ,a former for bending said wire over said anvil to form a staple, a driver for driving said staple, a cylinder, a piston in said cylinder for actuating said former, a second piston in said cylinder for actuating said driver, means for admitting tluid under pressure to said cylinder between said pistons, means for admitting fluid under a higher pressure to said cylinder on-the side of said second named p-iston opposite that side which is engaged by said rst named iluid, and means for adjusting the magnitude of said first named fluid pressure.

4. A stitching machine comprising, an anvil for supporting a length of stapling wire, a former for bending said wire over said anvil to form a staple, a driver for driving said staple, a cylinder, a piston in said cylinder for actuating said former, a second piston in said cylinder for actuating said driver, and means for separately supplying iiuid under different pressures to said cylinder to actuate said pistons.

5. A :stitching machine comprising, an anvil for supporting ,a length of stapling wire, a former for bending said wire over said anvil to form a staple and for engaging the work, a driver for driving said staple into the work, la cylinder, a piston in said cylinder connected to actuate said former, a second piston in said Kcylinder connected to actuate said driver, means for admitting compressed uid to said cylinder between said pistons, means for limiting the relative separation of said pistons, and means for admitting compressed fluid having a higher pressure than said rst named pressure to said cylinder on the side of said second named piston opposite that engaged by said rst named uid to produce working strokes of said pistons.

6. A stitching machine comprising, an anvil for supporting a length of stapling wire, a former for bending said wire over said anvil to form a staple and for engaging the work, a driver for driving said staple into the work, a cylinder, a piston in -said cylinder connected to actuate said former, a second piston in said cylinder connected to actuate said driver, means for admitting compressed fluid to said cylinder between said pistons, means for limiting the relative separation of said pistons, means for admitting compressed uid having a higher pressure than said rst named pressure to said cylinder on the side of said second named piston opposite that engaged by said rst named lluid to produce Working strokes of said pistons, and means for shutting off the ow of said rst named fluid to said cylinder when said second named fluid is so admitted.

7. A stitching machine comprising, an anvil for supporting a length of stapling wire, Ia former for bending said Wire over said anvil to form a staple and for engaging the work, a driver :for driving said staple into the work, a cylinder, a piston in said cylinder connected to actuate said former, a second piston in said cylinder connected to actuate said driver, means for admitting compressed uid to said cylinder ybe-tween said pistons, means for limiting the relative separation of said pistons, means for admitting compressed uid having la higher pressure than said first named pressure to said cylinder on the side of said second named piston opposite that engaged by said rst named uid -to produce working strokes of said pistons, and means for shutting oi the iiow of said second named uid and exhausting that uid from said cylinder when said driver reaches the end of its driving stroke.

8. A stitching machine comprising, an anvil for supporting a length of stapling wire, a former for bending said Wire over said anvil to form a staple and for engaging the work, a driver for driving said staple into the work, a cylinder, a piston in said cylinder connected to actuate said former, a second piston in said cylinder connected to actuate said driver, means for admitting cornpressed uid `to said cylinder between said pistons, means for limiting the relative separation of said pistons, means for admitting compressed fluid having a higher pressure than said lirst named lpressure to said cylinder on the side o'f said second named piston opposite that engaged by said iirst named fluid to produce working strokes of said pistons, and means for varying the magnitude of said rst named pressure.

9. A stitching machine comprising, an anvil for supporting a length of stapling wire, a former for bending said wire over said anvil to form a staple and for engaging the work, a -driver for driving said staple into the work, a'cylinder, a piston in said cylinder connected to actuate said former, a second piston in said cylinder connected to actuate said driver, means for supplying tiuid under pressure, means for admitting said fluid under low pressure to said cylinder between said pistons, and means for admitting said uid at a higher pressure to said cylinder on the side of said second named piston opposite to that engaged by said low pressure fluid.

l0. A stitching machine comprising, an anvil for supporting a length of stapling Wire, a former for bending said wire over said anvil to form a staple and for engaging the work, a driver for 'driving said staple into the Work, a cylinder, a piston in said cylinder connected to actuate said former, a second piston in said cylinder connected to actuate said driver, means for supplying uid under pressure, means for admitting said iluid under low pressure to said cylinder between said pistons, means for admitting said fluid at a higher pressure to said cylinder on the side of said second named piston opposite to that engaged by said low pressure fluid, and means for varying the magnitude `of said low pressure.

11. A stitching machine comprising, an anvil for supporting a length of stapling wire, a former for bending said wire over said anvil to form a staple and for engaging the work, a driver for driving said staple into the work, a cylinder, a piston in said cylinder connected to `actuate said former, a second piston in said cylinder connected to actuate said driver, means for supplying fluid under pressure, means for admitting said fluid under low pressure to said cylinder between said pistons, means for admitting said uid at a higher pressure to said cylinder on the side of said second named piston opposite to that engaged by said low pressure liuid, and means for limiting the movement of said rst named piston in response to said low pressure.

12. A stitching machine comprising, an anvil for supporting a length of stapling wire, a former for bending said Wire over said anvil to form a staple and for engaging the work, a driver for driving said staple into the work, a cylinder, a piston in said cylinder connected to actuate said former, a second piston in said cylinder connected to actuate said driver, means for supplying fluid under pressure, means for admitting said uid under low pressure to said cylinder between said pistons, and means for shutting off the iiow of said low pressure uid to said cylinder and admitting said uid at a higher pressure to said cylinder on the side of said second named piston opposite to that engaged by said low pressure uid to elect a forward stroke of both of said pistons.

13. A stitching machine comprising, an anvil for supporting a length of stapling wire, a former for bending said wire over said anvil to form a staple and for engaging the work, a driver for driving said staple into the work, a cylinder, a piston in said cylinder connected to actuate said former, a second piston in said cylinder connected to actuate said driver, means for supplying uid under pressure, means for admitting said fluid under low pressure to said cylinder between said pistons, means for shutting off the ow of said low pressure fluid to said cylinder and admitting said fluid at a higher pressure to Asaid cylinder on the side of said second named piston opposite to that engaged by said low pressure fluid to eiect a forward stroke of both of said pistons, and means for exhausting said high pressure fluid from said cylinder.

14. A stitching machine comprising, an anvil for supporting a length of stapling wire, a former for bending said Wire over said anvil to form a staple and for engaging the Work, a driver for driving said staple into the Work, a cylinder, a piston in said cylinder connected to actuate said former, a second piston in said cylinder connected to actuate said driver, means for supplying fluid under pressure, means for admitting said fluid under 10W pressure to said cylinder between said pistons, means for admitting said fluid at a higher pressure to said cylinder on the side of said second named piston opposite to that engaged by said low pressure uid, means l@ including a reciprocating member for feeding said stapling wire to said anvil, means for actuating said member in one direction by said law pressure Huid, and means for actuating said member in the other direction by said high pressure uid.

References Cited in the file of this patent UNITED STATES PATENTS 1,841,217 l Seizer Ian. 12, 1932 FOREIGN PATENTS 1,090,179 France Oct. 13, 1954 

